Inorganic Chemistry, Vol.47, No.16, 7074-7076, 2008
Fe2OCl62- salt formed by electrochemical oxidation of ethylenedioxytetrathiafulvalenoquinone-1,3-dithiolemethide in the presence of FeCl4- ion with a silicon wafer electrode
Electrochemical oxidation of a bent donor molecule, ethylenedioxytetrathiafulvalenoquinone-1,3-dithiolmethide (2), in chlorobenzene (PhCl)/ethanol containing NBu4FeCl4 as a supporting electrolyte is performed using an undoped silicon wafer electrode. Black crystals of 2(6) center dot Fe2OCl6 center dot 2PhCl are obtained that have a different molecular formula from that of 2(2) center dot FeCl4 crystals obtained previously using a platinum rod electrode. The new crystal has a structure composed of alternately stacked layers of 2 molecules and Fe2OCl62- ions, whose Fe-O-Fe bond is completely linear and for which the geometry around the Fe atom is almost tetrahedral. The electrical resistivity decreases with temperature until ca. 200 K, but below this temperature, it gently increases. The magnetic susceptibility (chi(p)) observed can be described by the sum of chi(p) obeying a Curie-Weiss law for the impurity spins and of chi(p) obeying a dimer model with a spin-exchange integral (J similar to -180 K) in each Fe2OCl62- ion, which is also weakly coupled to neighboring Fe2OCl62- ions through an additional exchange interaction.